The present invention relates to a method of conserving energy. In a more specific aspect the present invention relates to a method of utilizing the energy of a high pressure steam condensate. In yet another aspect, the present invention relates to a method of utilizing the energy of a high pressure steam condensate, from a heat exchange operation utilizing the steam as an indirect heating medium, to supply at least part of the energy necessary for a steam stripping operation.
Due to the rapidly dwindling supply of fossil fuels it is necessary that extended efforts be made to conserve energy where at all possible. This is particularly true in industrial operations. In light of this need, workers in the chemical and petroleum industries have recently extended great effort and have successfully reduced energy requirements and thus conserved fossil fuels in many operations. The present invention relates to one such energy conservation technique.
In numerous industrial operations, for example the separation of various multicomponent chemical streams by fractionation, evaporation and other well known techniques, steam at an elevated pressure is often utilized as a heating medium in indirect heat exchange with the material being separated. For example, in a fractionation column, such as a fractionation column for separating crude oils and products thereof into various desired products, material being fractionated is withdrawn from the bottom of the fractionating column, passed through a reboiler and back to a higher point adjacent the bottom of the column. In many cases, such a reboiler is heated by passing steam at an elevated pressure into the reboiler and collecting a high pressure condensate, at essentially the same pressure as the steam feed, from the reboiler. Normally, the high pressure condensate is then passed to a flash drum, to drop the pressure, and water under essentially atmospheric pressure and of substantially reduced temperature is either discarded or utilized in other operations where water is needed, depending upon the purity or quality of the water. This obviously is a waste of the energy represented by both the pressure and temperature of the high pressure condensate.
In still other industrial operations, constituents of relatively low boiling point are stripped from multicomponent liquids by countercurrent contact with a vapor. The most commonly used stripping medium in such cases, is low pressure steam. For example, in refinery operations steam is used as a stripping medium to remove hydrogen sulfide from sour water streams, in dephlegmators to strip light hydrocarbons from rich absorption oil, in solvent refining operations to remove traces of solvent from product streams, in deasphalting, dewaxing and deoiling of petroleum products, to strip various products and in numerous other such refining operations. Such operations obviously utilize substantial volumes of steam and accordingly substantial amounts of fuel to generate this steam.
As previously implied, there are also numerous operations in industrial operations which require substantial volumes of water. This is particularly true of waters of low mineral content. For example, in the petroleum industry, crude oil desalting operations require substantial volumes of fresh water, preferably of low mineral content, various boilers and cooling towers also require water, as well as various other operations. In many such cases, it is impossible to use process waste waters, which are contaminated with various chemicals and oils. However, it would be highly desirable if water, which has been used for various purposes and is in a relatively pure state, could be reused in other operations.
It is therefore an object of the present invention to provide an improved technique for conserving energy in industrial processes. Another object of the present invention is to provide an improved technique for conserving energy in petroleum refining operations. In yet another aspect the present invention relates to an improved technique for utilizing the energy of a high pressure steam condensate. Yet another object is to provide an improved technique for utilizing the energy of a high pressure steam condensate to supply the energy necessary for steam stripping various multicomponent materials. Another and further object of the present invention is to provide an improved technique for utilizing the energy of high pressure steam condensate to supply a substantial portion of the energy necessary for the steam stripping of multicomponent streams and to thereafter utilize recovered low pressure condensate for use in still other operations requiring substantial volumes of water.
These and other objects of the present invention will be apparent to one skilled in the art from the following description of the invention.